Preparation And Application Of Upconversion Luminescent Nanomaterials Based On Bismuth Fluoride

Rare earth upconversion nanomaterials have low toxicity,high photostability,excellent light source tissue penetration depth,and are widely used in biological imaging,sensing,drug delivery and cancer treatment.However,the large size,poor biocompatibility and low luminescence efficiency of traditional nanomaterials have severely limited their development.In this thesis,Upconversion Nanoparticles(UCNPs)with high luminescence intensity were prepared by regulating the synthesis conditions,and different recognition groups and loaded drugs were further modified on their surfaces,providing application materials for the detection of food nitrite and the diagnosis and treatment of cancer.The specific research contents and conclusions are as follows:1.The 808 nm near-infrared-responsive hydrophilic upconversion nanoparticles Ba₄Bi₃F₁₇:Nd³⁺/Yb³⁺/Er³⁺were synthesized by one-step solvothermal method.By changing the doping amount of rare earth ions,the reaction time and the types of surfactants,the effects on the luminescence intensity,size,dispersion and stability of UCNPs were explored.The UCNPs were characterized by fluorescence spectrometer,transmission electron microscope,scanning electron microscope and other test methods.The experimental results showed that changing the doping amount of rare earth ions,reaction time and surfactant had effects on the morphology,size and luminescence intensity of UCNPs.When the doping amount of rare earth ions Nd³⁺/Yb³⁺/Er³⁺is 4%/5%/0.5%,the reaction time is 21 h,and 0.6g polyethylene glycol(PEG)or 0.1g polyethyleneimine(PEI)is added,Ba₄Bi₃F₁₇:4%Nd³⁺/5%Yb³⁺/0.5%Er³⁺has uniform size and good dispersion,and has good upconversion luminescence properties.2.PEG modified Ba₄Bi₃F₁₇:4%Nd³⁺/5%Yb³⁺/0.5%Er³⁺(UCNPs@PEG)has good up-conversion luminescence performance as an energy donor and Neutral Red(NR)receptor.A fluorescent nano-sensor was designed for rapid detection of nitrite by fluorescence resonance energy transfer.The sensor is synthesized by PEG connection NR on UCNPs@PEG surface.Experiments show that:The concentration of NO₂^-was in the range of0-105?g/m L,and the fluorescence intensity ratio of UCNPs@PEG-NR changed linearly at546 nm and 653 nm.The minimum detection limit was 0.07?g/m L,and it was not affected by other interferences,showing high selectivity and sensitivity to NO₂^-.It provides an effective method for the specific recognition of NO₂^-in food.3.Pe I-modified Ba₄Bi₃F₁₇:4%Nd³⁺/5%Yb³⁺/0.5%Er³⁺(UCNPs@PEI)was used as a carrier to load photosensitivities Rose Bengal(RB)and Doxorubicin.To construct a nanocomposite of NIR Photodynamic therapy(PDT)combined with chemotherapy UCNPs@PEI-RBHA-DOX-PEG.Under the irradiation of 808 nm laser,UCNPs@PEI can activate RB to produce reactive oxygen species,which can be used for PDT.At the same time,it is planned to release DOX under the mild acid environment in tumor tissues to inhibit tumor growth through synergistic treatment.